Catalytic determination of nanogram amounts of Mn(II) by the aerial oxidative coupling reaction of 3-methyl-2-benzothiazolinone hydrazone with N,N-dimethylaniline

Summary

A new catalytic method for the determination of nanogram level of Mn(II) is developed, which is based on its catalytic effect on the aerial oxidative coupling reaction of 3-methyl-2-benzothiazolinone hydrazone (MBTH) withN, N-dimethylaniline (DMA) to form an indamine dye (λ_max=590 nm) in the presence of 1,10-phenanthroline (phen) as an activator. A detection limit of <0.05 ng Mn(II)/ml can be achieved and as low as 10⁻⁹ M Mn(II) can easily be determined by measuring the absorbance of the dye at a fixed time (50 min at 30° C). The proposed method was successfully applied to the determination of manganese in natural waters by using 0.02–4 ml of water samples without preconcentration and separation.